Microscopes/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, is looking into a microscope. An image shows plant cells as seen through the microscope's eyepiece. TIM: Neat. The plant cells are replaced by a typed letter. Tim reads it. TIM: Huh. Dear Tim and Moby, How does a microscope work? From, Quincy. Tim looks up from the eyepiece. He is seated at a table with the microscope. A robot, Moby, stands beside him. TIM: Well, there are lots of different kinds of microscopes. The most common are light, or optical, microscopes like this one. Tim points at the microscope on the table. TIM: It uses visible light and one or more lenses to magnify very small objects. MOBY: Beep. TIM: A lens is a piece of glass or other transparent substance that's curved to bend light. An animation shows a ray of light passing through a lens and bending so that the beam comes to a point as it exits the other side of a lens. A split screen shows two identical images of Moby. A lens appears in each image. One lens makes Moby look bigger, the other smaller. TIM: Depending on how it's made, a lens can make objects appear bigger or smaller. Light microscopes magnify small objects with a combination of convex lenses, which curve outwards, and concave lenses, which curve inwards. A convex lens and a concave lens appear on the screen as Tim describes them. MOBY: Beep. Images show a light bulb and a smiling sun. TIM: It all starts with a light source. Light is either projected directly through the lens, or bounced from a mirror mounted underneath the microscope's stage Images of microscopes and microscope parts illustrate Tim's descriptions. TIM: The stage is a platform with a small hole in it. Light comes through the hole and passes through a thin slice of the specimen you want to magnify. MOBY: Beep. TIM: The specimen is mounted on a slide, which is a rectangular piece of glass or plastic. After passing through the specimen, the light hits a series of objective lenses, which form an enlarged image of the specimen. The light from the objective lens set moves through the tube to the eyepiece. There, the image is further enlarged by the ocular lenses. Animations illustrate light from underneath the stage passing through the slide and lens. It is reflected through a series of lenses until it reaches the eyepiece. MOBY: Beep. TIM: No, that's not all there is to it. Tim looks into the microscope again. The image shifts to an out of focus specimen TIM: The image might still be out of focus. Tim points to the microscope's knobs. TIM: Knobs that move the objective lens set closer to and farther away from the specimen focus the image. Images show the specimen coming into focus as Tim adjusts the knobs. TIM: The coarse focus knob makes big adjustments to put the specimen into general focus, and the fine focus knob makes smaller adjustments. An image shows a side view of a microscope. Various parts of the microscope are labeled with graphics as Tim describes them. TIM: Oh, and that piece of curved metal that connects the stage to the tube? That's called the arm of the microscope. And the heavy piece of metal it all rests on is the base, which keeps everything stable. An image shows a Renaissance-era man looking intently into an early microscope. TIM: The optical microscopes we use today follow the same basic design of the first compound microscopes, invented sometime around 1600 in the Netherlands. MOBY: Beep. TIM: An inventor named Anton van Leeuwenhoek made the best microscopes in those early days, so he's known as the "father of microscopy." An image shows Anton van Leeuwenhoek. Another image shows a Renaissance-era man looking intently into an early microscope. TIM: But lots of inventors were building similar instruments around the same time, so it's not clear who made the very first one. MOBY: Beep. TIM: Yeah, light microscopes are just the simplest kind. Another common type is called an electron microscope. An image shows an electron microscope. The screen splits to show an electron microscope on the left and a specimen as seen through an electron microscope on the right. It looks sharp and detailed. TIM: These microscopes use a beam of electrons to produce really high-resolution images. They can magnify much smaller objects than optical microscopes because the electron wavelengths are much smaller than those of visible light. A third category of microscopes is scanning probe microscopes. These microscopes use an extremely fine point, sometimes a single atom wide, to see individual atoms or molecules on a material's surface. Images show a scanning probe microscope and a sharp, detailed specimen. MOBY: Beep. TIM: Well, all these high-tech microscopes can be used for lots of stuff. Anything from looking at grains of pollen in amazing detail to checking out the atomic structure of a certain material. Tim turns his head and sniffs. TIM: Hey, I think my frozen pizza's burning. I'll be right back. Tim stands and walks out of the room. Moby goes to the table and looks into the microscope's eyepiece. An amoeba looks up at him, annoyed. AMOEBA: Do you mind? Category:BrainPOP Science Transcripts Category:BrainPOP Transcripts Category:BrainPOP Engineering & Technology Transcripts